Various techniques exist for dehydrating food products. In conventional air drying, ambient air is passed over the product at low speeds and water is removed by evaporation, a process usually accelerated by heat delivered to the product by convection. The state-of-the-art in highest-quality food drying is freeze-drying, wherein sublimation of water from a frozen food product takes place at very low pressures and temperatures. Although freeze-drying results in nutritionally superior products to conventional air drying, the extreme operating cost and powdery texture of the products are prohibitive for many applications.
While growth of most organisms in an uncontrolled air environment is generally considered sufficient for commercial production, it is not necessarily optimal for all varieties of vegetation, fungi, small animals, insects, and microorganisms such as cyanobacteria for consumption or bacterial cultures for laboratory or industrial use. Conventional sprouting and micro-farming support systems sometimes include humidity and hydration control and air circulation functionality, but often fail to include oxygen and carbon dioxide control systems capable of varying these gaseous growth factors to optimal levels for a wide range of organisms with respect to growth rates and product quality. Controlled growth environments for other types of organisms suffer from similar drawbacks, most often failing to provide access to possible optimal gaseous concentrations that vary significantly from those in ambient air. Additionally, because of these drawbacks, periodic reduction of gases needed for sustained bacterial or insect growth in order to inhibit growth of undesirable organisms is not generally implemented as a standard function in most commercial equipment intended to support growth of commercial organisms and quality of products derived from them.